Panelboard with insulative snap-in support means

ABSTRACT

In an improved panel interior assembly of the type in which elongated bus bars are snap-fit into an insulating support structure a plurality of integrally molded pins are attached to the insulating support structure positioned to extend through holes in a pan to which the insulating support structure is to be attached. These pins are ultrasonically staked to securely hold the insulating support structure and bus bars attached thereto on the pan.

This is a division of application Ser. No. 07/782,188, filed Oct. 24,1991.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to electric distribution systems andmore particularly to an electric panel assembly in which bus bars areattached to a rigid support member which is attached to a supportingpan, both without the use of separate or external fasteners.

2. Description of the Prior Art

Generally, a panel assembly or load center contains several circuitbreakers connected to bus bars and serves as distribution centers inmain electrical circuits to many branch circuits. Panel assemblies areutilized in both one-phase and three-phase insulations wherein bus barsof positive and negative potentials are mounted on a dielectric supportstructure. Some panel assemblies of prior construction have thedisadvantage of including separate fastening means for fastening the busbars in place on the support structure, whereby additional costs andinconvenience is required in assembling the panel assemblies. Anothershortcoming of these prior art panel assemblies is that they alsorequire separate fastening means such as screws or rivets to attach thebus bar and support structure to a support pan.

Cooley in U.S. Pat. No. 3,769,553 discloses a bus bar and supportstructure which snap together. However, this device must be secured to asupporting pan with screws or other fasteners.

SUMMARY OF THE INVENTION

The present invention utilizes the snap-together bus bar and supportstructure of the type disclosed by Cooley in U.S. Pat. No. 3,769,553with an optional snap-in retainer to hold related components in place.Additionally, pins projecting from the support structure extend throughholes in the support pan. These pins are then ultrasonically staked tothe support pan.

Like Cooley, we prefer to provide an elongated insulating supportstructure and a pair of elongated bus bars. Each of the bus barscomprises an elongated main body part and a plurality of stab partsextending from the main body part in a spaced relationship spacedlengthwise relative to the main body part. The insulating supportstructure comprises a plurality of spaced ledge parts at each of twoopposite sides thereof. At each of the opposite sides of the insulatingsupport structure all adjacent spaced ledge parts are spaced by astab-receiving slot. The spaced ledge parts and the stab-receiving slotsof the two opposite sides are staggered lengthwise such that eachstab-receiving slot at each side of the insulating support structure isopposite a ledge part of the opposite side of the insulating supportstructure. The pair of bus bars are supported on the opposite sides ofthe insulating support structure with the spaced stab parts of each busbar being positioned in the associated slots and with the spaced ledgeparts of the associated side of the insulating support structure beingpositioned over parts of the main body part of the associated bus bar.The stab parts of the pair of bus bars are positioned in an interleavedrelationship aligned lengthwise along the insulating support structure.The insulating support structure has integrally molded projections whichfit into corresponding holes in bus bars. We also prefer to provideguide ramps near the stab-receiving slots to promote smooth, lowresistance assembly and a secure fit without the use of mechanicalfasteners. Molded pins extend from below the ledge parts to fit intoholes in a support pan. These pins are ultrasonically staked to securelyretain the bus supports and bus bars attached thereto. The improvedpanel assembly is expandable to satisfy a number of circuit capacityrequirements from 8 through 42 circuits with the insulating supportstructure being comprised of one or more identical sinosodial members.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a panel assembly constructed in accordance withprinciples of the subject invention;

FIG. 2 is a sectional view, taken generally along the line II--II ofFIG. 1;

FIG. 3 is an exploded view of a segment of the insulating supportstructure and associated portion of the bus bars;

FIG. 4 is a sectional view of the insulating support structure takengenerally along the line IV--IV of FIG. 3;

FIG. 5 is a bottom view of the insulating support structure; and

FIG. 6 is a perspective view of a present preferred snap-in retainer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, there is shown, in FIG. 1 a panel assembly 5comprising a sheet metal support pan 7 that may be supported in a loadcenter or panelboard enclosure in a well known manner. The support pan 7comprises a lower support part 9 and two upper support shelf parts 11. Aplurality of circuit breaker retaining hooks 15 are formed on the shelfparts 11 of the support pan 7.

An insulating support structure 17 is secured to the support pan 7 bymeans of pins 19 that pass through suitable openings in the support pan7. We also prefer to use a sheet of insulating material 12 between thesupport pan 7 and insulating support structure 17 with attached bus bars39 and 41. Ledge portions 23 of insulating support structure 17 extendover bus bars 39 and 41. We also prefer to provide at least one snap inretainer 18 to which terminal bars or other items may be connected. Theretainer fits between shelf 11 and a bus bar 39. A square or rectangulartab 22 is provided on the body 14 of retainer 18 which fits into acomparably shaped hole in support pan 7. At an opposite end a tab 16fits under a portion of bus bar 39. The top and sides of the retainermay have slots or holes into which a terminal bar or other item may fit.Although the retainer may prevent lateral movement of the bus bar 39, itis not intended to hold the bus bar 39 and attached support structure 17in place. To more permanently attach bus bars and support structure tothe pan 7 pins 19 which are ultrasonically staked into retainers 19a(see FIG. 2). Pins 19 are preferably cone pointed for ease of locationand insertion into holes in support pan 7. Moreover, we prefer that pins19 be at least 0.16 inches in diameter and 0.4 inches long. Thosedimensions assure that adequate material is present to ultrasonicallyform retainers 19a of sufficient diameter to be effective. Anotheradvantage is that if staking of a pin is inadvertently omitted, anunstaked pin of at least 0.4 inches will prevent assembly of theinterior to a panelboard. This feature insures a level of quality whichcould not be obtained with the use of mechanical fasteners.

The support structure 17 is an elongated member molded as an integralunit of an electrically insulating material. It comprises a main bodysupport part 21 extending the length of the structure 17 and a pluralityof ledge parts 23 extending outward at the front of the supportstructure 17 at each of two opposite sides of the main body support part21. A plurality of transversely extending stab-receiving slots 27 (seeFIGS. 3 and 5) are formed at each of the two opposite sides of thesupport structure 17 such that there is a stab-receiving slot 27 betweeneach of adjacent ledge parts 23 at each side of the support structure17. As can be seen in FIG. 3, the support 17 is constructed with thespaced ledge parts and the stab-receiving slots of the two oppositesides being staggered lengthwise such that each stab-receiving slot ateach side of the insulating support structure 17 is opposite a ledgepart 23 of the opposite side of the insulating support structure 17.Thus, the support structure has a sinusoid wave-like shape. We furtherprefer to provide mating lands 25 and 26 at each end of the insulatingsupport structure. This enables us to connect several insulating supportstructures 17-together to accommodate longer bus bars.

The insulating support structure 17 is molded such that there is afinger portion 29 extending from the supporting main body portion 21under each of the stab-receiving slots 27. The back surfaces of thefinger portions 29 and the back surface of the main body portion 21 areflat surfaces that rest on the pan 7 to support the structure 17. Asshown in FIG. 4, we prefer to provide a ramp 46 adjacent to each slot27. The ramp permits the bus bars 39 and 41 to be slid into theinsulating support structure and held firmly in place. The ramps 46 willassert pressure on the top surface of the bus bars 39 and 41 when thebus bars are assembled on the insulating support structure 17.

A pair of bus bars 39 and 41 are supported on the the insulating supportstructure 17 and are composed of electrically conducting material. Eachof the bus bars 39 and 41 (FIG. 3) comprises a flat elongated main bodyportion 43 and a plurality of flat stabs 45 that are bent over from themain body portion 43 to extend along planes generally normal to theplane of the main body portion 43 in the manner disclosed in FIGS. 2 and3. Each of the bus bars 39 and 41 is formed with a plurality of spacedapertures 47 between adjacent flat stabs 45.

The insulating support structure 17 is provided with a plurality ofprojections 49. Each projection 49 is located on the underside of ledgeportions 23 of insulating support structure 17 and is aligned with acorresponding opening 42 in the bus bars 39 and 41. When the bus barsare assembled with the insulating support structure 17, each projection49 snaps into place within its corresponding opening 42.

During the assembly of our interior assembly, the two bus bar structures39 and 41 are moved from the position in which they are seen in FIG. 3to the supported or mounted position seen in FIG. 1. During thismovement of the bus bars 39, 41, each of the stabs 45 moves into theassociated stab-receiving slot 27. In the final positions of the busbars 39 and 41 the stabs 45 are positioned in an interleavedrelationship aligned lengthwise along the center portion of theinsulating support structure 17 as seen in FIG. 1. The insulatingsupport structure 17, which is molded as an integral unit from anelectrically insulating material with some resiliency, such as athermosetting resin (for example, a phenolic resin), is then secured tothe supporting pan 7 by means of integrally molded pins 19. The bus bars39 and 41 rest on the flat front surfaces of the finger portions 29. Asthe bus bars, 39, 41 are moved into position sliding over the frontsurfaces of the finger portions 29, the ledge portions 23 flex upward.When the bus bars 39, 41 reach the fully mounted position seen in FIGS.1 and 2, the spring charged ledge portions 23 snap downward with theprojections 49 moving into the openings 42 in the bus bars 39, 41 toprovide an interlocking engagement between the insulating supportstructure 17 and the bus bars 39, 41 to thereby retain the bus bars inthe mounted position without the need of screws or other types ofseparate fastening members. The assembly is then placed on the supportpan 7 and insulating sheet so that pins 19 pass through holes in thesheet 12 and pan 7. Then the pins 19 are subjected to ultrasonic stakingwhich causes the pins Go be formed into retainers 19a. Those retainerswill have a diameter greater than the holes thus holding the bus bar andsupport assembly in place. The finished interior can then be mounted ina panel or load center in the conventional way. However, should any pin19 not have been staked the unstaked pin 19 will prevent proper mountingof the interior.

When the panel assembly is installed a plurality of circuit breakers 8are mounted on the assembly and connected to the conducting stabs 45 ina well known manner. During the mounting operation, the load end of thecircuit breaker is first moved into position with the associated hookportion 15, and thereafter the circuit breaker is pivoted down into thefully mounted position shown by dotted lines in FIG. 1. Each of thecircuit breakers 8 is provided with a well known type of solderlessterminal connector at the load end thereof to permit connection of thecircuit breaker in an electric circuit. Only two circuit breakers aredisclosed in FIG. 1, it being understood that at an installation aseparate pair of circuit breakers 8 may be connected to each of theconducting stabs 45. Thus, each of the conducting stabs 45 electricallyfeeds two circuit breakers in the panel assembly. The bus bars 39, 41,when connected in an electric circuit, are of opposite polarity, and itis necessary to provide adequate insulation and spacing between the busbars in accordance with electrical standards. It can be seen, withreference to FIG. 1, that each of the ledge parts 23, at each side ofthe insulating support structure 17, is opposite a stab receiving slot27 of the opposite side of the insulating support structure 17 so thateach of the stabs 45 is insulated from the main body portion of theopposite bus bar with the ledge part adjacent the stab 45 covering partof the main body portion of the opposite bus bar. The insulating supportstructure 17 and bus bars 39, 41 are so constructed and arranged thatthe bus bars, which are of opposite polarity, are adequately spaced andinsulated from each other.

The panel assembly illustrated in FIGS. 1 and 3 is an 8-circuitassembly. Two full size circuit breakers 8 or four half size circuitbreakers (not shown) are connected to each of the four stabs 45. A totalof eight full size circuit breakers can be mounted on the assembly tofeed and control eight circuits drawn off of the two bus bars.Alternatively, sixteen half size circuit breakers could be used to feedsixteen circuits. Single phase and three phase panel assemblies of thetype herein described are generally offered in different circuitdenominations. Manufacturers may supply panel assemblies comprising 8,12, 16, 20, 24, 28, 32, 36, 40 or 42 circuit breakers.

Although we have disclosed certain present preferred embodiments of ourimproved panel, it is to be understood that various changes in thestructural details and arrangement of parts thereof may be made withoutdeparting from some of the essential features of the invention.

We claim:
 1. A retainer for use in holding components in a load centerof the type having a subpan and at least one bus bar having an edgeportion spaced apart from and parallel to an interior wall of the subpanwherein the interior wall of the subpan has an opening therein, saidretainer comprising: a body adapted to be fit between the interior wallof the subpan and the edge portion of the at least one bus bar; a firsttab attached to one side of said body adapted to be fit within theopening of the interior wall of the subpan; and a second tab attached toan opposite side of said body adapted to be fit under the edge portionof the at least one bus bar.
 2. The retainer of claim 1 wherein saidbody has at least one aperture into which a component can be attached.3. The retainer of claim 1 wherein said first tab is a wedge.